Doug, you don't say where you are, so please understand that most everything I'll relate here I learned in hay fields in central Nevada.

We used three methods to control pocket gophers:

1. Cinch traps.

https://www.cinchtraps.com/product/cinch-traps-gopher-trap/

Darn, these things have gotten wicked expensive. In the 2000's, I'd buy them for $8/per. OK, if you use these, you want to drill a hole through the plate, so you can stake them down to the ground to keep them from walking off when cats, dogs or coyotes dig up your trap to get at the gopher. There are several other mods we'd do to them to make them as effective as possible, but I will tell you right now, these are the most effective gopher trap there is. I've used the rest, and they were mostly a waste of time. The Cinch traps work, and work well. Just stake them down. At $20+ per trap, I'd be pretty pissed off if even one of them walked away on me.

2. For heavy infestations (like you can walked across the field, hopping from one gopher mound to the next one), then the gopher getter with strychnine bait on groated oats with brown sugar mixed in works pretty well. I'd say that in one highly infested field we tunneled with the gopher getter, we got about an 80%+ kill on the first application, then we went after the stragglers with the Cinch traps.

https://elstonmfg.com/gopher-getters

3. Then we get to the fumigant tablets. We used Phostoxin tablets, which produce phosgene gas when they hit soil moisture. To use these, you dig out the gopher mount to get to the tunnel, toss a couple/three tablets down into the burrow, then stuff in some newspaper and cover the hole. Do not touch the tablets with your bare hands. These work much better than the propane blaster, or CO poisoning, etc. These also worked well for us in Belding ground squirrel elimination. These require a restricted applicator license, and in Nevada, we had to have a rodent certificate on top of the restricted license to use these. But they worked very, very well.

https://www.degeschamerica.com/products/fumigants/

Here is a different variation of the cinch trap I've used for 50 plus years with very good results - Much less expensive too . .  . .

It works on pocket gophers (the gophers that build the mounds and live in tunnels) and works on stripped gophers (the ones that live in abandoned pocket gopher mounds, or otherwise as know as "Goldy Gopher", Mn mascot).  Here, the pocket gophers will be most active in the mornings (dawn till 9 am ish to 3 or 4 pm till dusk). Dig open tunnel at mound, place trap down hole, gopher trys to fill opening and trap gets it around the neck or back side  (depends if it's investigating the light or pushing dirt back with it rear feet/legs).

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